Abstract
Single-site copper-based catalysts have shown remarkable activity and selectivity for a variety of reactions. However, deactivation by sintering in high-temperature reducing environments remains a challenge and often limits their use due to irreversible structural changes to the catalyst. Here, we report zeolite-based copper catalysts in which copper oxide agglomerates formed after reaction can be repeatedly redispersed back to single sites using an oxidative treatment in air at 550 °C. Under different environments, single-site copper in Cu-Zn-Y/deAlBeta undergoes dynamic changes in structure and oxidation state that can be tuned to promote the formation of key active sites while minimizing deactivation through Cu sintering. For example, single-site Cu2+ reduces to Cu1+ after catalyst pretreatment (270 °C, 101 kPa H2) and further to Cu0 nanoparticles under reaction conditions (270-350 °C, 7 kPa EtOH, 94 kPa H2) or accelerated aging (400-450 °C, 101 kPa H2). After regeneration at 550 °C in air, agglomerated CuO was dispersed back to single sites in the presence and absence of Zn and Y, which was verified by imaging, in situ spectroscopy, and catalytic rate measurements. Ab initio molecular dynamics simulations show that solvation of CuO monomers by water facilitates their transport through the zeolite pore, and condensation of the CuO monomer with a fully protonated silanol nest entraps copper and reforms the single-site structure. The capability of silanol nests to trap and stabilize copper single sites under oxidizing conditions could extend the use of single-site copper catalysts to a wider variety of reactions and allows for a simple regeneration strategy for copper single-site catalysts.
| Original language | English |
|---|---|
| Pages (from-to) | 8280-8297 |
| Number of pages | 18 |
| Journal | Journal of the American Chemical Society |
| Volume | 146 |
| Issue number | 12 |
| DOIs | |
| State | Published - Mar 27 2024 |
Funding
This manuscript has been authored by Oak Ridge National Laboratory, operated by UT-Battelle, LLC, under contract DE-AC05-00OR22725 and Pacific Northwestern National Laboratory, operated by Battelle, under Contract DE-AC05-76RL01830 with the US Department of Energy (DOE). This work was authored in part by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. This research is sponsored by the U.S. DOE Office of Energy Efficiency and Renewable Energy Bioenergy Technologies Office in collaboration with the Chemical Catalysis for Bioenergy (ChemCatBio) Consortium, a member of the Energy Materials Network (EMN). S.B., N.S., and J.W.H. were partially supported by the 2021–2022 Ralph E. Powe award. XAS measurements were performed on the MRCAT bending magnet line (10-BM). MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Microscopy was performed as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a U.S. DOE Office of Science User Facility by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. The authors thank Shawn K. Reeves for assistance with TEM sample preparation. The computational work is sponsored by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (BETO), at the Pacific Northwest National Laboratory (PNNL). Computational work was performed using the National Energy Research Scientific Computing Center located at the Lawrence Berkley National Laboratory provided by a user proposal and the PNNL Research Computing Facility. M.-S.L. performed part of the calculations and manuscript preparation of this work under the U.S. DOE Basic Energy Sciences, Chemical Sciences, Geosciences and Biosciences Division, Catalysis Program (FWP47319). Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 and PNNL under Contract DE-AC05-76RL01830 with the US Department of Energy (DOE). This work was authored in part by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).
| Funders | Funder number |
|---|---|
| National Renewable Energy Laboratory | |
| Energy Materials Network | |
| U.S. DOE Office of Energy Efficiency and Renewable Energy Bioenergy Technologies Office | |
| Office of Energy Efficiency and Renewable Energy | |
| Pacific Northwest National Laboratory | |
| Bioenergy Technologies Office | |
| Scientific User Facilities Division | |
| Office of Science | |
| Chemical Catalysis for Bioenergy | |
| Battelle | DE-AC05-76RL01830 |
| Basic Energy Sciences | FWP47319 |
| U.S. Department of Energy | DE-AC36-08GO28308 |
| Argonne National Laboratory | DE-AC02-06CH11357 |